Joel Onyango

Joel holds a Master of Science Degree with Distinction from IHE Delft Institute for Water Education, Delft, in Environmental Science specializing in Limnology and Wetland Ecosystems; and a Bachelor of Science Degree with First Class Honours from Egerton University, Kenya, in Applied Aquatic Science. He also received advanced training in aquatic system analysis and modelling from BOKU University, Vienna. Joel is employed at the African Centre for Technology Studies (ACTS) in Nairobi, Kenya as a research fellow in natural resources management and climate resilience programmes.

Prior to working at ACTS he worked at Egerton University, VIRED International, and Kenya Marine and Fisheries Research Institute (KMFRI). He has professional experience participating in research projects including ECOLIVE, EACIN, APPEAR SEAK-WARM and AfricaLics. His areas of interest include water resources pollution, water innovations and impacts of climate variability on inland water systems.

Currently, Joel is a PhD Fellow within the Aquatic Ecosystem Chair Group in the Water Science and Engineering Department of IHE Delft Institute for Water Education, Delft, The Netherlands. He is developing his research in combined toxicity of nutrients and pesticide residues in agricultural catchments, with a case study in Lake Naivasha catchment, Kenya.

Does combined nutrients and pesticides contamination enhance toxicity in aquatic ecosystems?

A complete list of publications can be found in Google Scholar.

Fertilizers and pest control are used in agricultural intensification to enhance agricultural production and economic returns. The need to improve food production and commercial benefits from agriculture has seen the demand for fertilizers and pesticides increase. Subsequently, risks associated with contamination by nutrients from fertilizers and pesticides from pest control have been elevated for recipient aquatic ecosystems. Moreover, the interaction between nutrients and pesticides in aquatic ecosystems potentially amplifies the contamination risk, but has attracted limited attention. This study aims to determine the response of aquatic ecosystems to combined contamination from nutrient and pesticide residues.

To achieve the aim, this study will carry out an environmental exposure survey to determine the concentrations of nutrients (nitrogen and phosphorus) and pesticides (cyfluthrin, cypermethrin, dichlorodiphenyltrichloroethane and lindane) in the aquatic ecosystem. It will measure the response of: (a) aquatic macroinvertebrate and phytoplankton/periphyton taxa and communities; and (b) ecological processes comprising primary production, respiration, reproduction and decomposition, to nutrients and pesticides contamination. The study will employ laboratory and in-situ experiments, and field surveys to determine the effect environmental exposure of a nutrients-pesticide combination to aquatic functional groups and ecological processes.

The research will: investigate the potential of a trait-based indicator for monitoring nutrient-pesticides combined effects and toxicity; produce a spatiotemporal water quality map indicating the pollution with reference to nutrients and pesticides contamination in an agricultural catchment of Lake Naivasha, Kenya; and document an ecotoxicological dose-response relationship profile for potential effects of a nutrient-pesticide combined contamination.